It is known that there is a positive mass and a zero 0 mass substance, and is there a negative

No, quality is defined as:

Mass in physics: The amount of matter an object contains is called mass. Mass does not change with the change of shape, state, spatial position of the object, is the basic property of the object, and is usually denoted by m.

The unit of mass in the International System of Units is kilograms, or kilograms.

It has to be mentioned that in physics mass is divided into inertial mass and gravitational mass. Inertial mass indicates the magnitude of the object's inertia, whereas gravitational mass denotes the magnitude of the gravitational force. In fact, through countless precise experiments it has been shown that these two masses are equal, that is, he is just different aspects of the same physical quantity.

There is matter in the universe with zero mass at rest, which is the photon. There are also a lot of things in the universe that are antimatter to each other. Antiprotons, antineutrons, and antielectrons form an antiatom if they combine like protons, neutrons, and electrons.

Matter made up of antiatoms is antimatter. When you look in the mirror, what if the one in the mirror you really exists and appears in front of you? Scientists have thought about it, and they call the one in the mirror "anti-you".

Scientists imagine a world far away that resembles ours, an anti-world made up of anti-stars, anti-houses, anti-food, and all the anti-matter. Antimatter is the opposite of matter in general, which is the main part of the universe.

The macroscopic matter around us is mainly composed of protons and neutrons with a positive number of baryons. Therefore, such matter is called positive matter, and matter composed of their antiparticles is accordingly called antimatter. From the point of view of particle physics, the properties of positive particles and antiparticles are almost completely symmetrical, so why is there a large amount of positive matter in nature, but almost no antimatter?

That's exactly what we're going to talk about now.

Fundamentally, antimatter is an inverted manifestation of matter. Albert Einstein once predicted the existence of antimatter based on the theory of relativity: "For a matter with a mass m and an electric charge of e, there must be a substance with a mass of m and a charge of -e (i.e., antimatter)".

Because particles and antiparticles collide together, like ice meets fireballs, they either disappear together, or they transform into other particles. So on Earth, antimatter will be merged as soon as it encounters other matter.

Therefore, there is positive and negative matter, but there is no positive and negative mass, and the positive and negative matter will have an annihilation reaction when they meet.

Do you understand?

No It seems that you are not very clear about the concept of quality yet.

Mass is an indication of how much matter an object contains. Mass does not change with the change of shape, state, spatial position of the object, and is the basic property of the object.

Just as a word has its antonyms, antonyms are also words. Antimatter is essentially a substance, but it can't be called that, we give it a name called antimatter. The matter we see now is called positive matter, and it is generally called matter directly.

The annihilation of positive and antimatter is not simply zero mass, but the release of all mass into energy, e=mc2, and finally it is the square of c, Einstein's famous energy formula, don't say you don't know (e is energy, m is mass, c is the speed of light), the collision of positive and antimatter with the same mass can completely convert the mass of both sides into energy (so mass is also a form of energy), our current nuclear fusion (that is, hydrogen bomb) only converts about three thousandths of the mass, The energy generated is already so amazing.

And photons just don't have rest mass, who said that photons don't have mass, if you want to dig deeper, let's study quantum theory and Einstein's theory of relativity.

Your imagination is appreciated, but remember that the law of conservation of energy is a premise of physics, an immutable truth. Of course, you can try to find facts to disprove them, but don't make inferences that contradict them before such facts appear, and then use them as a pre-imagination.

Theoretically, there shouldn't be.

First, proton reference levels (also known as zero levels) are selected from the acid-base equilibrium system, which are substances that exist in large quantities in solution and participate in proton transfer. Also called proton reference material. Lack of speed.

(1) From the meaning of the question, it can be seen that the gravitational potential energy EP increases by 15J, and the corresponding amount of negative work done by gravity increases the gravitational potential energy can know the work done by gravity -15J, with gravity doing work wg=-mgh, you can know that the height of the object rising is H=, and then there is the length of the object rising along the inclined plane l=h sin30 can know that L=5m, and the mechanical energy is reduced by 3J, you can know that the work done by gravity is -3J, and in this problem, in addition to gravity, the force that does the work is only friction, so we can know that the work done by friction is -3j, and the frictional force can be obtained by doing the work by friction wf=-fl, and the resultant force of the object f=mgsin30+f=ma, and the acceleration can be obtained as a=6m s2

2) For the whole sliding process, the kinetic energy theorem is obtained: mgssin30+fs=mv02 2, and s=100 3 meters is obtained, (s is the maximum height of the object rising along the inclined plane) and the kinetic energy theorem is reused for the whole sliding process: mgssin30-fs=mv2 2, and v=40 root number 6 can be obtained

Agree upstairs ... But the acceleration is miscalculated a=6

1.The object is affected by gravity and abrasive force in the process of diagonal upward motion, and the abrasive force leads to the reduction of its mechanical energy, e=fs

In fact, only 18j-3j=15j of the kinetic energy reduction is converted into gravitational potential energy, 15j=mgh=

Solve h=. There is a trigonometric function that calculates the distance of an object on a slope as s=h sin30°=.

The distance of 5 meters has less mechanical energy of 3j, 3j = f*5m. Derives f=. Its acceleration magnitude a=f m=, and the direction is opposite to the direction of its motion.

2.In other words, I feel that the first question is correct, why can't the data provided be used to calculate the second question???

If it is the left object and the right code, moving the game code is equivalent to adding weights to the right disk. In fact, even if the balance is not zeroed, by adjusting the balance nut is equivalent to adding weights to the left disk, the balance can still be balanced in the end.

Suppose the code is marked to the gram, the weighing object weighs 10 grams, and the weight balance is balanced with 10 grams on the right disk, but when you see the code without zero, you will think that it is a gram, so the measured value is greater than the true value.

It should be a balance that has been leveled.

Leave the rest of the matter aside.

That is, after the re-measurement, the disk object = the size of the right disk weight.

But in the end, the game code was added.

Then the measured value is naturally larger than the number of yards.

The balance room is equivalent to adding a small weight (as for why I asked the teacher, he said that I will know when I make the balance myself) The measured value is greater than the real value.

We know that moving the code to the right is equivalent to adding a small code to the right disk. When you forget to zero it, the right side (i.e. the side where you put the code) is biased at the beginning. And for the balance balance, can only move the balance nut on the left to the left, after the addition code is balanced, if the code returns to zero, the addition code will be balanced, the measured value will be larger, if not, the value of the code will be read more, and the measured value is larger than the actual value.

There is no thickness. This should be the areal density.

Momentum does not change .......

According to Newton's first law f=ma, the acceleration a=0 at this time, the object is moving in a uniform straight line or at rest, at this time v is unchanged, and the momentum p=mv is unchanged.

It can also be considered directly with the momentum theorem. By the momentum theorem, ft= p. The resultant external force f is 0, so the change in momentum is p=0. That is, the momentum does not change.

In fact, considering the bull one and the momentum theorem, although the starting point is slightly different, the essence is the same.

It must not change, when the object is equal to zero by the resultant external force, there is Newton's first law to know that the object will move in a straight line at a uniform speed or at rest, and the momentum of the object: p=mv, m is constant, and the v ratio changes, so the momentum of the object does not change.

The principle that the speed of light cannot be exceeded is not necessarily true.

But quality has no real meaning to nature.

So I personally don't think there is any negative value of mass, according to the general theory of relativity, everything in the universe is the action of gravity, so mass does not exist.

All that exists is the mass converted into gravity (gravity!!

There is antimatter. But it's not simply a negative quality.

Going back in time is now just a hypothesis, provided that the speed of light is exceeded .

Whether it can exceed the speed of light is also a question.

You can't just say that you have stepped back in time. That's just Einstein's hypothesis.

According to Einstein's equation e=mc 2, the greater the velocity of an object, the greater the energy, the greater the mass, the energy required for acceleration is infinite, so any object with mass cannot exceed the speed of light, but what will happen in the future is still unknown, and the same is true for the time rewind caused by exceeding the speed of light.

Hold your arms and you'll know if you try faster-than-light motion and then tell us

No, the speed of light cannot be surpassed.